The main goal of this research is to investigate whether the Principle of Contrastive Usage holds for the linguistic input that young children receive from their parents. This principle predicts that words which are used contrastively are not only different but also similar in meaning. That is, contrasted words will tend (a) to be semantically related, and (b) the semantic relation will tend to be the coordinate relation, since coordinates are conceptually similar (e.g., cat and dog both refer to a kind of animal). Related research questions are what forms of 'contrasting' and/or 'correcting' can be distinguished in the input to children, and what role individual and situational variables play in the occurrence of these forms. The spontaneous speech produced by two mother-child dyads, in natural interaction at home, was analysed. Speech samples had been collected at regular intervals over the second half of the children's third year. Only nouns were examined. Two communicative situations were distinguished, 'free conversation' and 'visually guided conversation' (book reading, making a jig-saw puzzle). Several subcatego-ries of contrast and correction were discriminated. Subcategories shared by both are corrective explicit contrast and corrective implicit contrast. A contrast-specific subcategory is descriptive contrast, correction-specific subcategories are global negation, specific negation, correction by demonstration, and correction by acknowledging similarity. It was found that contrast and correction are strongly correlated in the input, and tend to go together. However, it was also found that contrast but not correction is sensitive to aspects of communicative situation, whereas correction but not contrast is sensitive to individual differences. As to the character of the relationships between the contrasted terms, it was found that the coordinate relation is indeed predominant, most notably in descriptive contrast. Additionally, it was found that parents, when correcting their children, have a clear preference for explicit over implicit contrast when there is any kind of similarity between referents involved, i.e., when the relation between contrasted terms is either coordinate (conceptual similarity) or is based on perceptual or functional similarity.